Determinants of ventricular function in pressure-overload hypertrophy in man.

Abstract

To determine if impaired cardiac performance in patients with pressure-overload hypertrophy is due to inappropriately high wall stress rather than to depressed contractility, hemodynamic and geometric factors were assessed in 14 patients with isolated aortic stenosis and various degrees of left ventricular failure (ejection fraction range 0.19-0.85). Poor correlation occurred between aortic valve area, peak left ventricular systolic pressure, or left ventricular mass and measures of ventricular function. There were close correlations between circumferential wall stress and ejection fraction (r [correlation coefficient] = 0.96) and fiber shortening velocity (r = 0.91) in patients with aortic stenosis. Force-velocity-shortening relationships in 6 normal control subjects fell on the same regression line as that of patients with aortic stenosis and force-velocity-shortening relationships of patients with primary myocardial failure differed. A major determinant of wall stress was the ratio of left ventricular will thickness to cavity radius (h/R). Patients with h/R ratios > 0.36 had higher values for ejection fraction (0.61 .+-. 0.06 vs. 0.36 .+-. 0.07, P < 0.05), Vcf (0.79 .+-. 0.10 vs. 0.39 .+-. 0.04/s, P < 0.05) and stroke work index (71 .+-. 10 vs. 45 .+-. 9 g-m/m2, P < 0.005) than those with lower ratios. Left ventricular wall thickness and geometry are closely correlated with ventricular performance in patients with pressure-overload hypertrophy due to aortic stenosis. Poor cardiac performance in some patients may be due to inadequate hypertrophy (or inappropriate geometry) rather than to depression of myocardial contractility.